Process of making heat dried detergent compositions containing form ii sodium triphosphate



Dec.

Filed June 4, 1948 16, 1952 E. s. HIZER 2,522,063

PROCESS OF MAKING HEAT DRIED DETERGENT COMPOSITIONS CONTAINING FORM 1:SODIUM TRIFHOSPHATE 2 SHEETSSHEET 1 flare fi w/z flare/#04; w UV Z655/d% Wave/31017 All 77029 a/{yfiy I //00/5 QYWWM fife/2362132912625Mrzejs ONS ' 16, 1952 4 E. 5. HI

- PROCESS OF MAKING HEAT DRIED DETERGENT couposrrr 2 SHEETS-SHEET 2 ICONTAINING FORM II SODIUM TRIPHOSPl-IATE Filed June 4. l9

Standard X-Ruy Patterns of Sodium 'Triand Pym-Phosphots Na P O I N0 P O'SH O 3 m Zileri 6- 125x67 0J2, 9'- wa sm W Patented Dec. 16, 1952PROCESS OF MAKING HEAT DRIED DETER- GENT COMPOSITIONS CONTAINING FORM IISODIUM TRIPHOSPHATE Elbert S. Hizer, Cincinnati, Ohio, assignor to TheProcter and Gamble Company, Ivorydale, Ohio, a corporation of OhioApplication June 4, 1948, Serial No. 31,174

3 Claims.

The present invention relates to a method for the manufacture ofdetergent mixtures containing alkali metal triphosphates (sometimescalled alkali metal tripolyphosphates), and particularly to theincorporation of slowly hydrating anhydrous triphosphates in aqueousdetergent compositions.

Some varieties of triphosphate in finely divided form exhibit theundesirable property of forming lumps that dissolve very slowly in watereven though the mixture is well stirred. The tendency to form lumps oragglomerates, I have found, varies with the phase or form of crystallinestructure of the phosphate. Thus I find that finely dividedtriphosphates containing substantial amounts of the high temperatureform, usually referred to as Form I, show a very marked tendency to lumpwhen stirred into aqueous fluids even though the mixture is stirredvigorously. However, I have found that comparably finely dividedtriphosphates of the low temperature phase usually referred to as FormII, show little or no tendency to agglomerate under like conditions, andthe present invention relates to the use of these Form II triphosphatesin the manufacture of detergents.

Prior to the present invention, however, triphosphates of the Form IIvariety have had the objectionable tendency, when used in themanufacture of heat dried detergent compositions, of producing powdersof a sticky nature that are not free flowing and that cake badly underslight pressure in storage bins, packing machines and in packed cartons.

In order to avoid a damp product which would lump and ball much worse,extreme atomization has been used to facilitate the spray drying of suchcompositions causing them to be fragile and dusty as well as sticky. 7

By sticky I refer to an objectionable tendency of the individual spraydried granules to agglomerate with one another, and compact, cake oradhere to other objects that the granules moveover or contact.

It is found that the Form II varieties, in marked contrast to the Form Ivarieties, hydrate extremely slowly (even though they have a higherimmediate solubility than the Form I varieties!) This slow hydrationbehavior appears to be responsible for the aforementioned difiicultiesheretofore encountered when Form II triphosphates have been used inmaking detergent compositions, doubtless because a major portion of thewater in the final dried product has been present as free water ratherthan as water of hydration.

It is an object of this invention to provide a method for themanufacture of non-sticky detergent compositions using Form IItriphosphates and to reduce the dustiness of said detergentcompositions.

More specifically the invention contemplates substantially completehydration of Form II triphosphates in aqueous fluid detergent mixturesso as to prevent stickiness and reduce the dustiness of the drieddetergent composition made therefrom.

I have discovered that suitable aging of aqueous fluid detergentmixtures containing Form II triphosphate prior to heat drying gives theunique and unexpected result of eliminating the sticky propertiesotherwise obtained in the heat dried detergent composition preparedtherefrom. The time and temperature conditions of this aging arecritical, as will subsequently be explained.

I have also discovered that this same aging greatly reduces thedustiness of the detergent product. The starting effect of aging isshown in a product, which was made from an aqueous detergent mixturecontaining Form II sodium triphosphate in particulate form that was agedfor 8 hours before spray drying. It was a freefiowing, hard, non-sticky,tough, granular, nondusty product that did not break down during thepackaging operations. It had a dry feel even though it contained 10 percent moisture. In direct contrast an identical batch of the samecomposition that was not aged before spray drying gave a sticky productthat caked and lumped badly during the packaging opera-'- tion eventhough it contained only 3 per centmoisture. In addition the granuleswere dusty and so fragile that they broke down to give more dust duringthe packaging operation.

I have further discovered that substantially complete hydration of thesodium triphosphate .to the hexahydrate should be accomplished duringthe above mentioned aging period in the aqueous fluid detergent mixture.

In the accompanying illustrations Figure 1 illustrates the conditions oftime and temperature wherein approximately '10 per cent reversion ofsodium triphosphate occurs during aging in the aqueous detergentcompositions.

Figures 2 to 5 represent X-ray diffraction patterns characteristic offour different phosphates as follows:

Figure 2, anhydrous sodium triphosphate in the phase known as Form I, V

Figure3, anhydrous sodium triphosphate in the phase known as Form II,

Figure 4, sodium triphosphate hexahydrate, and

Figure 5, anhydrous sodium pyrophosphate.

In this specification and the appended claims I employ the termdetergent to designate organic detergents, including:

(1) Ordinary'soaps such as the alkali metal salts of the higher fattyacids that may be ob-, tained from naturally occurring plant or animalesters or that may be produced synthetically (e. g.

by oxidation of petroleum, or by hydrogenationof carbon monoxide by theFischer-Tropsch proc ess) resin acids and/or naphthenicacids.

(2) Synthetic organic detergents characterized by their high solubilityin water; their resistance to precipitation by the constituents of hardwater,

and their surface active and efiective detergent properties, whichinclude:

(a) Anionic detergents (excluding true soaps), such as water-solublesalts of sulfuric and phosphoric acid reaction products of alkyl and"substituted alkyl compounds containing from 8 to 18 carbon atoms in thealkyl group,

(b) Non-ionic detergents, such as the reaction products of higheralcohols and higher fatty acids with. considerable amountsof alkyleneoxides,

(c) Cationic detergents, such as certain quaternary ammonium'groups andcertain amine groups neutralized with acids each of which is preferablyemployed in its water-soluble salt form, bearing in mind, however, thatsome cationic detergents have but limited utility in strongly alkalinecom position.'

Numerous examples of such synthetic. organic detergents are mentioned inLinds U. '8. Patent We include in the term detergent composition and/ordetergent mixture, in'addition 'tdone or more of the above detergents,-alkaline builders? or detergent improving agents such as alkalinecarbonates, silicates, phosphates and'. borates and/or such compounds asthe perborate s, persulfates and percarbonates; also organic builders,and. perfumes, coloring matter, preservatives, and

other Substances, mem er. mm deter ent.

compositions.

X ray diffraction patterns showthat the Forms I and II (see Figures 2ancl 3) represent two dif ferent phases of sodium triphosphate havingdistin'ctly different crystalline patterns. Those spacings which areparticularly useful for the identification of these forms in thepresence of other phosphates are indicated on thepatterns,

(8. g; 258,358, 3.71 and 8.1 angstro'n r units in Figure 3 2(NaSP30m-II) )I Bot forms take. on water to Iorm one and the samehydrate (NaaPaoio' 6H2Q) however, the heat of solution of Form II ismuch lower than that of Form I, while the Pimmediate solubi1ity"of'FormII in water is greater than that of Form I. immediate solubility ismeant the amount of sodiumtriphosphate in solution at the end of 10minutes solution time, (i. erthesolu bity determined by inixinginto100,;milliliters of water. more than the amount ofsodiumtriphosphaterequire'dtoniake a saturated solution and coolingto"25''. (3., and at the end of 10 minutes filtering, and evaporating at105 C. a weighed portion of filtrate followed by drying at 500- C. Theweight of dried material obtained per 100 gm. of solution is called theimmediate solubilityf). Although various samples of Form II will showidentical X-ray diffraction patterns they are frequently observed todifferwidely their im;

Table I v Form I II II Variety Rapidhy- Moderate hy- Slow hydrator.drator. drator. Immediate sulubility in 20 30.

gm. per gm. Water soln. 25 0. Hours for hydration in 1% 5,

aqueous detergent mixure.

This table shows two typical examples of the numerous variationsencountered in the time,

needed for hydration of Form II sodium triphosphate. These hydrationperiods were determined by measuring the time'required to reachsubstantially maximum mass viscosity of the detergentmixture containing thetriphosphate as said.

phosphate absorbed the free Water in the mixture:

and converted to the hexahydrate. These measurements were made with acommercially avail-1;

able instrument called the Brabender Plastoe. graph, which recordscontinuously the torsion moment required to rotate a. pair of agitatorsins the viscous mixture being examined.

I have found that the hydration of the. tri-.

phosphate in the aqueous detergent mixtures. can readily be accomplishedby aging, within the tem-.-. perature range of to 200 F., in a manner.adapted to prevent settling and separation of the undissolved salts.

merous other devices, e. g. screw conveyors. or long pipelines, whereinsufficient storage timeis to be had to permit substantially completehygdration to the hexahydrate.

Sodium triphosphateis a metastable materialin water solution. Ithydrolyzes or reverts,slow-. 1y to form normal and acid salts of other,phOSf.

phoric acids, usually having a higher degree of molecular hydration.Thus: excessively. high temperatures or long aging periods, are to be.avoided since the larger amounts of reversion,

products obtained thereby reduce; the. efficiencyand other desirableproperties of q the. final do; tergent composition. In the practice of:this in:- vention it is my purpose to so regulate the op:

erating conditions that reversion of thetriphosphate will be less than10 percent. The curye in Figure 1 shows conditions of time-and ternperaturefor the aging opfi iation at which;ap; proximatelylo per centreversion is to;be;,ex;- pected.

The invention will be. better understoodiiro n the following examplesinwhich allcompositiops are given in terms of percentage by Weight-or;

parts by weight.

Example I .-38 parts of a slowly hydrating; 7

Form II sodium triphosphate, having a part1 size such that it would passthrough a, Tyle x with 58 parts of an aqueous fluid containing;

standard 35 mesh screen, were thoroughly; mix

The aging may be eflect-... ed in a vessel equipped With agitators or innuwater and 24% of sodium alkyl sulfate prepared by sulfating the fattyalcohols obtained by the reduction of coconut oil, and 4 parts of sodaash were then added. The somewhat thin slurry obtained therefrom wasmixed thoroughly for 20 minutes and then aged for 6 hours at 165 F.during which time it was agitated by a slowly turning (15 R. P. M.)paddle type agitator that served to keep the slurry well mixed withoutincorporating large amounts of air. During the aging the slurry became aviscous but yet pumpable mixture which was then spray dried, in wellknown manner, yielding a highly satisfactory, rapidly dissolving,efiicient detergent composition in solid granular form, that was freeflowing, comparatively dustless, non-sticky and composed of toughgranules that did not break down to any significant amount duringsubsequent packaging operations. Analysis showed it to contain 9%moisture.

The marked benefit obtained through the aging process is shown bycomparing the product in Example I with a product obtained by spraydrying a like, aqueous, detergent-triphosphate mixture that had not beenaged. The latter was a sticky, fragile and dusty product, the particlesof which caked and lumped, and broke down badly to form more dust duringthe packaging operation. This product contained only 3% moisture.Another portion of the same unaged slurry that was spray dried so as toleave 9% moisture in the product gave a damp material that balled badlywhen handled.

Example II.--32 parts of a moderately slowly hydrating Form II sodiumtriphosphate, having a particle size such that it would pass through aTyler standard 35 mesh screen, were thoroughly mixed with 48 parts of anaqueous fluid containing 60% water and 23% sodium alkyl sulfate, and 14parts of an aqueous fluid containing 65% water and 16.4% of alkylbenzene sulfonate, to which were added 5 parts of soda ash. The somewhatthin slurry obtained therefrom was aged by slowly agitating it for atotal of 4 hours at a temperature of 170 F., during which period itgradually became a viscous but yet pumpable mixture. Said slurry wasthen spray dried in well known manner yielding a highly satisfactory,rapidly dissolving, efficient detergent composition, in solid granularform, that was free flowing, comparatively dustless, non-sticky andcomprised of tough granules that did not break down to any significantamount during subsequent packaging operations. Analysis showed it tocontain moisture.

A product obtained by spray drying a slurry of like composition, but notaged, was a sticky, fragile and dusty product, the particles of whichcaked and lumped badly during the packaging operation. This productcontained only 4% moisture.

Example III.--36 parts of a poorly hydrating Form II sodium triphosphatewere thoroughly mixed with 59 parts of an aqueous fluid containing 60%water and 24% of sodium alkyl sulfate, and 5 parts of soda ash were thenadded. The somewhat thin slurry obtained therefrom was mixed thoroughlyand then aged for 5 hours at 160 F. during which time it was agitated bya slowly turning (15 R. P. M.) paddle type agitator that served to keepthe slurry well mixed without incorporating large amounts of air. Duringthe aging the slurry gradually became a viscous but yet pumpable mixturewhich was then dried as a film or thin sheet over steam heated rolls,

efficient detergent composition, in diminutive flake form, that was freeflowing, non-sticky and comprised of tough particles that did not breakdown to any significant amount durin subsequent handling. Analysisshowed the product contained 14% moisture.

Example IV..29 parts of a slowly hydrating Form II sodium triphosphate,having a particle size such that it would pass through a Tyler standard35 mesh screen, were thoroughly mixed with 68 parts of an aqueous fluidcontaining 65% water and 16.3% of alkyl benzene sulfonate, to which wereadded 5 parts of soda ash. The somewhat thin slurry obtained therefromwas mixed thoroughly for 20 minutes and then aged for 6 hours at F.during which time it was agitated by a slowly turning (15 R. P. M.)paddle type agitator that served to keep the slurry well mixed. Themixture, which became more viscous during aging, was then spray dried inwell known manner, yielding a highly satisfactory, rapidly dissolving,effiicient detergent composition in solid granular form, that was freeflowing, comparatively dustless, non-sticky and comprised of toughgranules that did not break down to any significant amount duringsubsequent packaging operations. Analysis showed it to contain 7%moisture.

A product obtained by spray drying a slurry of like composition, but notaged, was a sticky,

fragile and dusty product, the particles of which lumped very badlyduring the packaging operation. This product contained only 3% moisture.

It will be noted that in the detergent composition of each of theforegoing examples the Form II triphosphate is a major component andwas, in fact, present in greater quantity than the organic detergent.

I have found that an aging period of six hours at 165 C. is, in mostcases, sufiicient for the treatment of commercial phase II sodiumtriphosphate used in the preparation of detergent compositions ashereinbefore described, and that with occasional lots, which representmoderately fast hydrating varieties, as little as one to two hourstreatment will sufiice; however, since an intent of the aging is tosubstantially complete the hydration of the triphosphate to thehexahydrate I generally employ such periods of time as are necessary tocompletely hydrate extremely slowly hydrating varieties of Form II thatare infrequently encountered.

In the preceding specific examples detergents of each of the varioustypes enumerated in de-- fining the term may be substituted for thedeproportion of triphosphate is used, very little of the triphosphate isin solution at any one time during the processing operations, most of tbeing merely suspended as a slurry. Thus to insure the desired productsolubility rate the triphosphate used should in general have a particlesize no larger than that desired in the final product.

This invention in its broad aspects is not restricted to the manufactureof detergent mixture'si containing in,..addition.- tootheorganicr dee.tergentonly; sodium triphosphatee but .mayalso be. applied ;in themanufacture .of 1 detergents comprising triphosphates .of potassiumand'other. alkali: metals.

tion in; which thealkali metal triphosphatemay be; included, suclr as.flakes. threads, powdersi or.

spraydriedlforma It-js to, be .understood that .the .foregoing. more.

articularly described.processes; are to, be. con..-. sidered as,illustrative of .the preferred .method only; such changes. andmodifications therein. are contemplated; as,v would; normally occurv tothose; skilled in therart, to. which. the invention 4 relates,

Having thus describedmyinvention, what. I claim; and desire to securebyv LettersPatentis: 1. Inthe process. of; manufacturing: a. heat drieddetergent. composition. substantially. free ofdust; and: of stickiness,and. caking properties,

the steps of incorporating: Form. II1sodium..tri.-. phosphate ina fluidmixture. containing. essen-.

tially -an; organic; detergent. ofzthe. group consist-- ing of;. alkali.metal soaps and: Water soluble nonsoapwsynthetic detergents. and morethan. sufficient: w'aterto effect substantially complete-11y" dration ofthe said triphosphate-to the hexahydrate, the amount, of, said "triphosphate incor: porated beinginexcessof the. amount of detergent;agitating and. aging the. mixture withinthe temperature range'of 120 to200 F. for-at least one. hour. and until hydration to-the hexahydrate issubstantiallycompleteas determine} bleby measuring the time required toreach a maximumin a mass -.viscosity test of a likemi g ture. of. saidcomponents, but no longer than thattimerepresented by the pointon thecurve.

in Figure 1 which corresponds to 10 percent reversion of= thetriphosphate at the aging tem perature employed; and heat drying theaged mixtureto the'solid form."

2: n th r qce e o manufacturing a heatdried detergent me e i n .s h antl y reeof du t and of stickinessand caking properties the steps ofincorporating Form 'I'I 'so'diunr triphosphate in a fluid detergentmixture containingnasf the .w te rsqlub ..salt of amember selected fromtheglfgl ll. consisting .50 ,.mi .tu'r s thereci containingfrom sto'18ca 0 atszms intheallgyl active detergent ingredient of Sulfuric tie Pre i cts. o a k l. and s b stituted- 'allg'yl *cornpounds,

roup, and morethan su tertoefie'ct ls fi i llrz mele e.hrdretien e idiphosp at g h hexah-x rate..theamemt e Nor f is. it, limited to. any par.ticular type of manufactured .detergentcomposie;

.. 5 I iaiif ih eee ei hqern rated.bein .i e ceseoi the amountof:detergent;- agitating and aging the mixture within the temperaturerangeiof 120 to 200?:F.afor at.least oneihour and until hydration to thehexahydrateis substantially complete as determinable by measuring thetime required to reach -amaximum in a mass'viscosity test of alikemixture of said-components, but no longer than-that timerepresentedby the point on the curvein Figure- 1 which corresponds to 10percent reversion of the triphosphate'at' the aging" temperatureemployed; and heat dry-ing'the aged mixture tothe solid form-.

3. In the process of manufacturinga heat dried detergent compositionsubstantially free of dust and-of-stiokiness and caking-properties; thesteps of incorporating Form II-sodiumtriphosphate in a fluidmixturecontaining essentially an organic detergentof the group consisting ofalkali-metal soaps and water soluble-non-soap" syntheticde tergents andmore than sufiicient water to efiegt substantiallycompletehydration ofthe said triphosphate; the amount-of said triphosphate incorporatedbeing in excess of: the amount of detergent; agitating and aging themixture withp in the temperature range of l29 200? F; for at,

least one hour and until hydration is substantially complete asdeterminable by measuring the time required to reach a maximum in amass. viscositytestof a like mixture of saidcomponents, but no longerthan that time represented by the point onthe curvein Figure 1 whichcorresponds to the aging temperature employed; and heatdrying the agedmixture to the solid form.

EDBEBT HIZER REFERENCES: CITED' The follow-ing references ;;areof-reoord in the file of this patent:

1. IN THE PROCESS OF MANUFACTURING A HEAT DRIED DETERGENT COMPOSITIONSUBSTANTIALLY FREE OF DUST AND OF STICKNESS AND CAKING PRPERTIES, THESTEPS OF INCORPORATING FORM 22 SODIUM TRIPHOSPHATE IN A FLUID MIXTURECONTAINING ESSENTIALLY AN ORGANIC DETERGENT OF THE GROUP CONSISTING OFALKALI METAL SOAPS AND WATER SOLUBLE NONSOAP SYNTHETIC DETERGENTS ANDMORE THAN SUFFICIENT WATER TO EFFECT SUBSTANTIALLY COMPLETE HYDRATION OFTHE SAID TRIPHOSPHATE TO THE HEXAHYDRATE, THE AMOUNT OF SAIDTRIPHOSPHATE INCORPORATED BEING IN EXCESS OF THE AMOUNT OF DETERGENT;AGITATING AND AGING THE MIXTURE WITHIN THE TEMPERATURE RANGE OF 120* TO200* F. FOR AT LEAST ONE HOUR AND UNTIL HYDRATION TO THE HEXAHYDTRATE ISSUBSTANTIALLY COMPLETE AS DETERMINABLE BY MEASURING THE TIME REQUIRED TOREACH A MAXIMUM IN A MASS VISCOSITY TEST OF A LIKE MIXTURE OF SAIDCOMPONENTS, BUT NO LONGER THAN THAT TIME REPRESENTED BY THE POINT ON THECURVE IN FIGURE 1 WHICH CORRESPONDS TO 10 PER CENT REVERSION OF THETRIPHOSHPATE AT THE AGING TEMPERATURE EMPLOYED; AND HEAT DRYING THE AGEDMIXTURE TO THE SOLID FORM.